Upgrading specs help

Alright im thinking about upgrading my pc i used to programs to scan my pc Belarc Advisor and www.crucial.com/systemscanner. Now when i did this i found to odd things first i have 1gb of ram installed right but both of these programs are reporting it wrong for some reason, i havent fooled around with my pc in upgrading it since i bought it about 1yr ago only once when the memory it came with one was wrong and they replaced it and just put it in and it works so i dont know why it is reporting at 128 slock 1 and 2 but iwant to upgrade my pcs memory

Now as u can tell by these reports what i find odd is that both are reporting 128 mb int two slots when its suppose to be 512 on two slots
much help would be apreciated thank you. I read the memory tutorial though it did not help and found out my pc takes DDR PC3200,DDR PC2700,DDR PC4000